Manufacture of shoe stiffener material



106. cowi PosmN3, COATING 0R PLASTIC. I

Patented 1m 10, 1933 i 1,893,924 I V-niiuimb "UNITED, :STATI'ES'JFPATENTome]; o'. woonnurrior nssrenoa'ro may a.

f Id 7' 1:}. Application hled iiuawist aubfljjgerial8o;1556;615. f i

There are various of shoeistifiener land mouldable by'the actionoftheusualnitro- V v materials which go intothe'manufacturei ofcellulose orldellu'loid solvents. I have found shoe stifiener .parts,lsuch as box toes d that when shoe'stifiener material consisting, 4 icounters. -.One of the important kinds pi lgfior example, of wovencotton fabric coated or pg 5 shoe .stifiener material containsrdistribut-pll'impregnated with fcelluloidnis treated with '55.

' ed therethrough nitrocellulose .or celuloid, a co nHo WOIution and gwhich renders the material susceptible of then 1'18 ,-not only is thestifi'ener material ing converted intoa limp andmouldable con- -renderedmore stable; but acquires high fire= dition byithe use of V8.11011Sorganics olvents. -.resis'tance. One of; the difiiculties presented Itis the practice, therefore, to treat bo' x,toe ,'Ijwheii sodium silicate'aloneis used, however, Q9 or counter blanks of suchmaterial with a 'isthatthestifiener material containin' nitr suitable organic solvent torender them pellulose d es not acquire'the desire ;1im'p'- andmouldable, in which condition theyiare; nessand mouldabilityupontreatmentwith fl assembledqandmouldedwith-the'shoe'u ra -nitrocellulosesolvents" Evidently; the so-, c2 and then permittedgtoiset-in place isdiuni.= ,'silic'at'e not onlyfor insfirep roof sheath- 5. conditioningtreatment f'th solvents may. be *ings on the combustible fiber,but' alsodeposits performed either at :the factorywherethe 011, thenitrocelluloseas continuous films or shoevstifienerjmaterial is made,oratfthe'coatingswhich arepenetrated only slowlyfifm shpe 7' factory.When the; shoe astiflener at all, bylthenitrocellulose solvent. Ihaveblanks are :treatedbdore shipping tohthe i discovered. that theimp'ermeability .o. the 7.9 shoejaetory; they are usually packed inhergzsodium'silicate 'films'is'destroyed when a crysa; meticallysealedoontainersso that theycgn tailliizablealkaline s alg preferably onewhichf be maintained 'in limp andmouldable con' f crystallizes withvvaterofhydration or cr'ys' dition until they areapplied tothe shoelgrgt, tallization, is used as Wllas the sodium sllig'l m A jnaj'or ,objec.tion, especially fromthe oate solution; gApparentl psalts'whichcrys;:15

pointof view of-the shoe manufacturer, to, talliaewith wateroifhydrationor crystallizev shoezstifiener partscontainingnitrogellulosggtionbreakmpthe continuity of the sodiumjn; celluloid hflsmmfi betwil e fihw e enifil s fli nflyt P -L. t. they are highlyinflammable ,and giv elrise nitrocellulose solvents tocomein contact E"-to serious fireandexplosionhaz'ard,especially,c-Quicklyqiwith-thenitrocellulose and thusgto. 9;; when thenitrocellulose is] resent, as;is'cusggelatixiize the samef practicallyas quicklyds 3 tomarily 'the case, inla fa ric'pri ejlt ,fl' fqnosodiumsilicate were.gpresent. ,It may f, itself is m e f i h 'l ib eemetrielfl lbs fl -tthe'nry ta e s ks p h gellulosef'fibe'r. It? st. bebi'rl e ontinu ity ofigh Esofiiumsilicatefilms byab- 110;

y that-shoe 'stifienermaterial cotitaiiiingfnitro tractingvwatertherefrom-and therebysatis- 11; cellulqsbr'elhfldid isnot',onlyfdangerous ifying its owngwatergof crystallizationfbut fbecause it is readily set-on fire through'pa ',this merel lyadvanced-,as speoulation gor lessnes's, but that 'iiiherentlydangeroustheory. ,T y i on account of the liability ofihesitroeuui' while varlousa a me salts which crystal :33

lose to undergo i-spontaneous decompositioii line .fr'omgaoue isolutionwithwater iof n l -i x f .f 'y ta e i n may pl y d, LP R FtQ I havefoundthat it is possibl usesalts of the'chiarflc klioi thewateroluble Aif j shoe'stifienr material: consisting"*of aiabric" phosphat'esandfcarbonates, firstgifor the :rea-s' t orrfelt rioundatiomassociatedwith "initroeel ison thatthey canlbe'admixed with thesodium lulose orcelluloidiby the of various .chemasilicate' solutioni form" a; single-vsolution 1 icals of alkaline man-e Theyalkalineihwithout anyobservablereaction; and,'second,+ 1; chemicals {which vhave found to beierb'ecan'se they; themselves," are highlyincom+ F J; sirablearethoseiwhichimpart-tothestifienerv bustible and-olimp'artthis propertyto theistifis 1 materialiire resistance-end;at;thesame enenmateiiialfiImthis connectiomitiswelltoim time permit the material to'be'renderedlimp observe that a soluble phosphate, such as "I: i l Y I 4 p a c I I vV E i W w and a M u WM A Examincs I '6 ution-soaked fa incombustiblegasestwhich inhibit combustion. Thus, ammonium carbonate undergoesdecomposition when heated to liberate'bdzh carbon dioxide and ammonia,both of which are incombustihle and accordin ly smother a fire, In pointof fact, the soluble carbonates, especially ammonium carbonate, alonemay he' used to impart high fire resistance to the stifiener material,valthough I prefer to use ithem conjunctively with a solution of sodiumfsilicate, because the combination of the two fsalts is more efiectivein this respect than the carbonate alone. The soluble phosphates,however, such as tri-sodium phosphate, should he used with the silicate,for the reason "that such phosphates alone are not suiiicientlyeffective in lowering the combustihility of stiifening materialcontaining nitrocellulose, even though the foundation alone might berelmdered non-combustible by such phosphate a one. While it is possibleto practise various spelcific procedures falling within the ambitof theresent invention, a procedure which bath of the solution at a rate toensure satisfactory impregnation, and finally over a drum dryer. Thedried material is incombustible to such an extent that when a flame isapplied thereto only smoldering takes 121m andthereis a derided tendencyfor the smoldering to die out. fact, when the flame is removed from thematerial, such little cmnbustion as has been set up tends to cease, andno creeping of the glow to the unfired portions of the material isobservable. In-the absence ofmy treatment, when thenitrocellulose-containing fabric is set on fire, "even the h the flameis extinguished, the residual g owcontinues to creep to the unf'firedpoitionsof the fabric with attendant liberation of considerable heat andwhite, choking fumes of nitrous oxides.

Aside from the incombustibility of the "treated material when it isdeliberately fired, there is no tendency whatever for it to undergospontaneous combustion and ignition. "In other words, the agentsincorporated into the material have a tremendous stabilizing eflectthereoan by virtue of the fact that "they are alkaline and thus canneutralize nitrous oxide {nines into which thenitrooellulose mighttend'to decompose with the evolution of heat undercertain conditions.

The principles of the present invention ex tend to'various types offoundations into "which nitrocellulose or celluloid has beenineorporated to form shoe stifi'ening material. For example, the shoestiffening material quay be one rwhichhas been fabricated on a ermachine and throughout which nitro- Ihas een found to give eminentlysatis'fac- P P tory results is carried out about as follows. A single ormulti-ply cotton 'fabriowhich has been coated or impregnated with a solution of nitrocellulose 'or celluloid and .then

dried to form shoe stifiener material, ma he submersed in a concentratedsolution of 0th tri-sodium phosphate and sodium "silicate. 'The solutionmay, for example, be made up '4 by adding parts of sodium silicate of 38"'Baum and parts 'of tri-sodium phosphate (Na5PO .12H O) to partsofwatenpreferably with the application of heat so as to promote rapid dssolution. The sodium silicate and tri-sodium phosphate formahomogeneous, colorless and limpid solution. In order to promotepenetration of the solution into the fabric, the solution is preferablyheated to and'kept at about boiling temperature F.),-at whichtemperature a-"period of immersion of only about 30 seconds issufiicient to associate sufiicient salt with thenitrocellulose-containing fabric to imart the desired propertiesthereto. The soric may :then be dra ned jfree of excess solution anddried. l -he impgegnation and drying-of thestifiening marial ma beractised as a continuous i-pr'o- ".cess, ast e stiffening material .mayibe uncellulose in fibrous or precipitated form has beenincorporated, asby mixing the fibrous or precipi ated nitrocellulose with unnitrat- "edcellulose fiber'in the beater engine prior to sheeting-" '80, too, afoundat on fabricated onmaohineryof the textile or papermaking may becoated or impregnated with a nitrocellulose or celluloid solution anathen driedto produce shoe s'tifiening mafteriahi hny one of thesefoundations containingnit rocellulose or celluloid either as alcontinuous phaseoby virtue of treatment with a solution ofnitrocellulose or celluloid,

'ofr as a discontinuous phase'yhy virtue of the" incorporation thereintoof fibrous nitrocellu- ,los e .ojr ;precipitatejd nitrocellulose, may bei bi' ed tb-th s b l nd fi p ng tjreatmenta m mention. I 7.1 a I wouldnot regard it as a'departure from ethei t a sa s-my v n it n w gmimpregnate the -;nitrooellulose-eontaining foundation withthe sodiumsilicate so- \lution and then with a aqueous solution of the.iz'rystallizable alkaline salt, such as trisodium phosphate, z irith orwithout interme- :diate' 'drying,butl it obviously preferable usethe twosalts'in a single :solution and as woimd from a r 1 h P e h h a te fi tmii m h imman" 106. COMPOSITIONS, COATING R PLASTIC.

tion in a single step and then to follow such impregnation by drying.

In the appended claims, I am using the term nitrocellulose as meaningeither nitrocellulose as such or nitrocellulose which has beencompounded with other materials, such as camphor, to produce celluloidor analo ous nitrocellulose compounds.

claim:

1. F ire-resistant shoe stifiener material comprising a fibrousfoundation associated with nitrocellulose as a stiffening agent andimpregnated with a mixture of both sodium silicate and a crystallizedalkaline salt, said material being rendered limp and mouldable bytreatment with a nitrocellulose solvent.

2. F ire-resistant shoe stiffener material comprising a fibrousfoundation associated with nitrocellulose as a stiffening agent andimpregnated with a mixture of both sodium silicate and a hydrated,crystallized alkaline salt, said material being rendered limp andmouldable by treatment with a nitrocellulose solvent.

ting

Examiner cellulose with a concentrated solution of both process whichcomprises impregnat-.

ing a fibrous foundation containing nitrocellulose with a concentratedsolution of both sodium silicate and tri-sodium phosphate, dryin theimpregnated foundation, and cutthe dried foundation into shoe stifienerparts.

10. A process which comprises impregnata fibrous foundation containingnitrocell ose with an made u of b agueous solution a out 59 parts 0water, 20 garts of s ium silicate 0 8 aum, an parts of tri- (NM Q- Zdrying the impregna oundation, and cutting the dried foundation intoshoe stiffener parts.

In testimony whereof I have afiixed my signature.

FRANK o: WOODRUFF.

3. F ire-resistant shoe stiffener material 5 comprising afibrousfoundation associated with nitrocellulose as a stiffeningagent-and impregnated with a mixture of both sodium silicate and acrystallized water-soluble carbonate, said material being rendered limpand mouldable by treatment with a nitrocellulose solvent.

6. Fire-resistant shoe stiffener material i z comprising a fibrousfoundation associated v I i with nitrocellulose as a stiffening agentand impregnated with a mixture of both sodium silicate and crystallizedammonium carbon: ate, said material being rendered limp and 1 vmouldable by treatment with a nitrocellulose solvent.

7. A processv which comprises impregnate ing a'fibrous foundationcontaining nitrocellulose withlan aqueous solutionof both sodiumsilicate anda vcrystalliz able alkaline if salt of the character of thesoluble phosphates and carbonates, and drying the impregnate foundation.

8. A process ing a fibrous foundation containing nitro-

